Article
Physics, Fluids & Plasmas
Yann-Edwin Keta, Etienne Fodor, Frederic van Wijland, Michael E. Cates, Robert L. Jack
Summary: We analyzed the collective motion that occurs during rare events in systems of active particles, and discussed the associated dynamical phase transition to collective motion. A finite biasing field is needed to induce spontaneous symmetry breaking, and particle alignment is studied both for a two-particle system and for many-particle systems using an optimal-control representation of the biased dynamics. Additionally, a fluctuating hydrodynamic theory is proposed to capture the emergence of polar order in the biased state.
Article
Mechanics
Tal Bar, Baruch Meerson
Summary: This article extends the geometrical optics of Brownian motion by accounting for diffusion inhomogeneity in space, exploring situations where the diffusivity of the Brownian particle depends on one spatial coordinate. One of the findings describes 'Brownian refraction', an analogous phenomenon to the refraction of light passing through a boundary between media with different refractive indices.
JOURNAL OF STATISTICAL MECHANICS-THEORY AND EXPERIMENT
(2023)
Article
Physics, Fluids & Plasmas
Diego M. Fieguth, Timo Schlachter, Daniel S. Brady, James R. Anglin
Summary: This study examines a Hamiltonian system representing an active particle that can move in noisy and dissipative environments by drawing energy from an internal depot. Despite energy dissipation to the environment, it can help stabilize the dynamic process of the active particle.
Article
Chemistry, Physical
Lorenzo Caprini, Alexander R. Sprenger, Hartmut Loewen, Rene Wittmann
Summary: We propose a new model that generates a complete family of descendants flexibly. This model unifies two commonly used models for active matter, revealing a deep stochastic relationship between them. It provides more suitable models for various active matter systems and explains their characteristic distribution features. We evaluate the model in a reference example and demonstrate the transition in the shape of positional density distribution.
JOURNAL OF CHEMICAL PHYSICS
(2022)
Article
Physics, Fluids & Plasmas
Elena Sese-Sansa, Demian Levis, Ignacio Pagonabarraga
Summary: In this study, a model system of repulsive self-propelled disks in two dimensions with ferromagnetic and nematic velocity alignment interactions is comprehensively analyzed. It is found that strong alignment leads to orientational order, while moderate alignment with high self-propulsion results in motility-induced phase separation (MIPS). The microscopic theory derived for these systems accurately predicts the occurrence of MIPS, showing the predictive power of such theories in describing complex active matter systems.
Article
Physics, Multidisciplinary
Hidde D. Vuijk, Holger Merlitz, Michael Lang, Abhinav Sharma, Jens-Uwe Sommer
Summary: Active particles, when bound to passive objects, exhibit chemotaxis and move towards regions of higher activity. Connecting active particles into chains can lead to a transition from antichemotaxis to chemotaxis, allowing protoforms of life to locate sources of nutrients without sensory-motor apparatus.
PHYSICAL REVIEW LETTERS
(2021)
Article
Physics, Fluids & Plasmas
Sanku Paul, J. Bharathi Kannan, M. S. Santhanam
Summary: Quantum directed transport can be achieved in chaotic systems by breaking symmetries and introducing interactions, allowing for control of the currents.
Article
Mathematics, Applied
Mateusz Wisniewski, Jakub Spiechowicz
Summary: In this study, a paradigmatic model of nonequilibrium statistical physics is reinvestigated, involving an inertial Brownian particle in a symmetric periodic potential subjected to both a time-periodic force and a static bias. The researchers focus on the phenomenon of negative mobility, where the average velocity of the particle is opposite to the constant force acting on it. It is found that in the weak dissipation regime, thermal fluctuations induce negative mobility more frequently than in the case of stronger dissipation.
Article
Multidisciplinary Sciences
Sergi G. Leyva, Ralph L. Stoop, Ignacio Pagonabarraga, Pietro Tierno
Summary: In this study, we demonstrate the significant impact of the dispersing medium on the collective dynamics of interacting Brownian particles in a ratchet transport system. The long-range hydrodynamic interactions (His) result in a speed-up effect, leading to a higher translational speed and the formation and growth of clusters perpendicular to the driving direction. This research sheds light on the role of the dispersing medium in the dynamics of driven colloidal matter and the morphology of clusters.
Article
Physics, Multidisciplinary
Wei-Jing Zhu, Bao-Quan Ai
Summary: We studied the rectified transport of underdamped particles subject to phase lag in an asymmetric periodic structure. We observed that the average velocity can reverse with small self-propelled force when considering the inertia effect, while particles always move in the positive direction with large self-propelled force. The introduction of phase lag causes particles to follow circular orbits and suppress polar motion. Additionally, this can adjust the direction of particle motion. There exists an optimal value of polar interaction strength at which rectification is maximal. These results have important implications for various applications, such as spatial sorting of particle mixtures and separation based on physical properties.
Article
Chemistry, Physical
E. A. Lisin, O. S. Vaulina, I. I. Lisina, O. F. Petrov
Summary: This paper examines the underdamped active motion of self-propelled particles in a liquid and discusses situations where the overdamped approximation is not valid. A generalized analytical equation is proposed, which is confirmed by numerical simulations.
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
(2022)
Article
Physics, Multidisciplinary
Constantin Rein, Martin Kolar, Klaus Kroy, Viktor Holubec
Summary: Autonomous active Brownian ratchets rectify particle motion by spatially modulated but stationary activity. This rectification principle is similar to the ratcheting induced by steric obstacles in microswimmer baths. The efficiency of rectification is highest at intermediate activities, reaching a few percent for ratchets with simple wedge-shaped low-activity regions.
Article
Physics, Fluids & Plasmas
Koushik Goswami
Summary: We study the underdamped motion of a passive particle in an active environment using the phase space path integral method. The probability distribution function of position and velocity for a free and a harmonically bound particle is derived. Two similar OUP models are considered to investigate the effects of inertia and other parameters on the particle dynamics. The work fluctuations of a harmonically trapped particle are also analyzed, and the fluctuation theorem of work is validated with an effective temperature in the steady-state limit.
Article
Chemistry, Physical
Elena Sese-Sansa, Demian Levis, Ignacio Pagonabarraga
Summary: This article discusses a dynamical field theory for self-propelled particles subjected to generic torques and forces. By coarse-graining their microscopic dynamics, the study investigates the instabilities of macroscopic and finite structures, and the influence of intrinsic torques on phase separation and non-equilibrium patterns.
JOURNAL OF CHEMICAL PHYSICS
(2022)
Article
Mathematics
Zdzislaw Brzezniak, Ben Goldys, Martin Ondrejat, Nimit Rana
Summary: We study the stochastic wave map equation with solutions on a d-dimensional compact Riemannian manifold. We prove the existence of a unique, global, and strong solution in local Sobolev spaces. The main contribution of this paper is the proof of the Large Deviations Principle for solutions when the noise vanishes.
JOURNAL OF DIFFERENTIAL EQUATIONS
(2022)
Article
Multidisciplinary Sciences
Yuting Li, Guenther Turk, Paul B. Rohrbach, Patrick Pietzonka, Julian Kappler, Rajesh Singh, Jakub Dolezal, Timothy Ekeh, Lukas Kikuchi, Joseph D. Peterson, Austen Bolitho, Hideki Kobayashi, Michael E. Cates, R. Adhikari, Robert L. Jack
Summary: The study presents a Bayesian inference methodology for quantifying uncertainties in epidemiological forecasts, specifically for epidemics modeled by non-stationary, continuous-time, Markov population processes. The method's efficiency is derived from an approximation of the likelihood using a functional central limit theorem, which is valid for large populations. The methodology is demonstrated by analyzing the early stages of the COVID-19 pandemic in the UK, utilizing age-structured data for deaths.
ROYAL SOCIETY OPEN SCIENCE
(2021)
Article
Physics, Mathematical
Oliver Niggemann, Udo Seifert
Summary: Investigation on the thermodynamic uncertainty relation in the (1 + 1) dimensional KPZ equation with finite spatial interval reveals two distinct regimes of the relation separated by a critical coupling parameter. Analytical exploration of the asymptotic behavior below and above the critical threshold is presented, along with comparison to numerical simulations.
JOURNAL OF STATISTICAL PHYSICS
(2022)
News Item
Physics, Multidisciplinary
Patrick Pietzonka
Summary: The macroscopic properties of active matter can be attributed to the non-equilibrium character and handedness of interactions between individual particles.
Article
Multidisciplinary Sciences
Patrick Pietzonka, Erik Brorson, William Bankes, Michael E. Cates, Robert L. Jack, Ronojoy Adhikari
Summary: Bayesian inference methods were applied to study the change in lethality of COVID-19 in late autumn 2020 in the UK. Models allowing change in infection fatality rate (IFR) showed consistently higher model evidence and inferred a near two-fold increase in IFR. Despite the introduction of new variants, the models suggest that the increase in IFR may have occurred prior to the dominant strain change.
Article
Physics, Multidisciplinary
Patrick Pietzonka
Summary: The thermodynamic uncertainty relation is a universal trade-off between driving an autonomous system and the precision of output observable. It has been proven for discrete systems and overdamped Brownian motion, but the validity for underdamped Brownian motion remains uncertain. Through constructing a counterexample inspired by a pendulum clock, we disprove the conjecture and show that the uncertainty relation is broken by underdamped harmonic oscillators in thermal equilibrium.
PHYSICAL REVIEW LETTERS
(2022)
Article
Physics, Multidisciplinary
Jann van der Meer, Benjamin Ertel, Udo Seifert
Summary: This work investigates the waiting time distributions between consecutive transitions in a partially observable Markov network. An entropy estimator is formulated using the ratios of waiting time distributions to quantify irreversibility. Depending on the complexity of the underlying network, criteria are formulated to infer whether the entropy estimator recovers the full physical entropy production or provides a lower bound. Additionally, estimators for the network topology are derived using an equivalent semi-Markov description. The study provides a unifying mathematical framework for entropy estimators and clarifies the meaning of formal versus physical irreversibility.
Article
Physics, Multidisciplinary
Arya Datta, Patrick Pietzonka, Andre C. Barato
Summary: Macroscopic cyclic heat engines have been a major motivation for the emergence of thermodynamics. In recent years, cyclic heat engines that have large fluctuations and operate at finite time have been studied within the framework of stochastic thermodynamics. This study examines the concept of cyclic active heat engines for systems with hidden dissipative degrees of freedom and introduces a general second law for active heat engines using a known inequality in stochastic thermodynamics.
Article
Physics, Multidisciplinary
Josip Augustin Janes, Cornelia Monzel, Daniel Schmidt, Rudolf Merkel, Udo Seifert, Kheya Sengupta, Ana-Suncana Smith
Summary: This article investigates the influence of active fluctuations on reaction kinetics in a medium, using the cell membrane as a paradigmatic example. By deriving binding and unbinding rates from first principles and establishing a model that incorporates both thermal fluctuations and active fluctuations, the authors show that these fluctuations directly impact protein association and dissociation rates.
Article
Physics, Multidisciplinary
Timur Koyuk, Udo Seifert
Summary: This paper investigates the properties of the thermodynamic uncertainty relation (TUR) in complex systems with many degrees of freedom. By analyzing the entropy production of mixtures of driven particles, an explicit expression for the optimal estimate of total entropy production is derived and applied to driven lattice gases.
PHYSICAL REVIEW LETTERS
(2022)
Article
Biochemistry & Molecular Biology
Benjamin Ertel, Jann van der Meer, Udo Seifert
Summary: In this study, we propose a method to extract the step size and stalling force of a molecular motor without relying on external control parameters. The method is non-invasive, operationally accessible in experiments, and can potentially be applied to any model describing the dynamics of molecular motors. Our results are confirmed by extensive numerical simulations.
INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES
(2023)
Article
Physics, Multidisciplinary
Jann van der Meer, Julius Deguenther, Udo Seifert
Summary: Irreversibility is quantified by entropy production, which can be estimated through measuring antisymmetric observables like current. A general framework is introduced to infer a lower bound on entropy production by measuring time-resolved statistics of events with any symmetry under time reversal, including time-symmetric instantaneous events. Markovianity is emphasized as a property of certain events rather than the full system, and an operationally accessible criterion for this weakened Markov property is introduced. The approach is based on snippets, which are particular sections of trajectories between two Markovian events, and a generalized detailed balance relation is discussed.
PHYSICAL REVIEW LETTERS
(2023)
Article
Physics, Fluids & Plasmas
Lukas Oberreiter, Udo Seifert, Andre C. Barato
Summary: Biochemical clocks are crucial for all living systems and can only oscillate coherently for a limited number of times when isolated from external signals and subject to fluctuations. Moreover, these clocks can only oscillate if they consume free energy. We propose a universal bound that determines the minimum amount of free energy required for a certain number of coherent oscillations.
Article
Physics, Fluids & Plasmas
Benjamin Ertel, Jann van der Meer, Udo Seifert
Summary: This article discusses the relationship between entropy production and mean and variance of steady-state currents in semi-Markov processes, as well as the uncertainty relation in coarse-grained Markov processes generated by semi-Markov descriptions. The article introduces a crucial condition in thermodynamic consistency and presents some alternative derivations of results.
Article
Physics, Fluids & Plasmas
Benedikt Remlein, Volker Weissmann, Udo Seifert
Summary: In this study, we analytically determine the quality factor of oscillations induced by driven Fokker-Planck dynamics along a periodic one-dimensional potential in a noisy environment. We extend this approach to investigate motion along a noisy two-dimensional limit cycle and apply it to the Stuart-Landau oscillator and the Brusselator chemical clock model. Our approach complements the existing framework based on Hamilton-Jacobi theory and is compared with numerical results.
Article
Physics, Fluids & Plasmas
Patrick Pietzonka, Jules Guioth, Robert L. Jack
Summary: In this study, the statistical behavior of the number of times a non-equilibrium system traverses cyclic sequences of states is investigated, with a focus on the joint distribution of forward and backward instances within cycles. The results, described by universal formulas dependent on cycle affinity, are compared to fluctuation theorems and generalized for families of cycles relevant under coarse graining. Application of large deviation theory to this cycle-counting problem is discussed as well.
